JPH04259831A - Temperature detecting apparatus - Google Patents

Abstract

PURPOSE:To detect and display the disconnection of a lead wire and to repair the lead wire beforehand by taking out a first and a second lead wires from one terminal of a temperature sensor, and a third and a fourth lead wires from the other terminal, connecting the second and third lead wires via a resistance, connecting the first through fourth lead wires in series, and connecting a display device in series to a group of the lead wires. CONSTITUTION:A connector CN2 connects two lead wires taken out from each terminal of a temperature sensor TD to a temperature detecting circuit 4. A light emitting diode D1 is turned ON by a current flowing in a group of series lead wires constituted by taking out a first and a second lead wires from one terminal of the temperature sensor TD and a third and a fourth lead wires from the other terminal. Both ends of a resistance R5 constituting part of the group of series lead wires are connected to the second and third lead wires. The first lead wire is connected to a resistance R4 and the fourth lead wire is earthed. If any of the lead wires is disconnected, the current is not allowed to flow in the light emitting diode D1, and therefore the light emitting diode D1 is turned OFF, informing the disconnection. Since the disconnection of the lead wire is detected and displayed, it is possible to repair the lead wire beforehand.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to fire alarms, automatic fire extinguishing, etc.
The present invention relates to a temperature detection device that operates by detecting temperature with a temperature sensor.

0002

2. Description of the Related Art A conventional temperature detection device will be explained with reference to FIG.

In FIG. 3, 3 is a temperature detection circuit, 1 is a power supply terminal, 2 is a control signal output terminal, TD is a temperature sensor,
CN1 is a connector connecting temperature sensor TD and temperature detection circuit 3, IC is a comparator, R1 to R3 are comparator I
This is the bias resistance of the input terminal of C.

[0004] The inverting input terminal of the comparator IC has the following characteristics:
A voltage obtained by dividing the power supply voltage by resistors R2 and R3 is applied, the power supply voltage is applied to the non-inverting input terminal + via the resistor R1, and the non-inverting (power supply voltage) is output to the control signal output terminal 2. has been done. When the temperature rises and the temperature sensor TD closes, the non-inverting input terminal + is grounded, and an inverting (ground) signal is output to the control signal output terminal 2. However, if the lead wire connecting the temperature sensor TD and the connector CN1 is disconnected, no inverted output is output from the control signal output terminal 2.

[0005]

[Problem to be Solved by the Invention] The temperature sensor TD is installed in a place where it can easily detect heat, and the temperature detection circuit 3 is installed in a safe separate place, and these are often connected with a long lead wire. Sometimes the wires got caught in the machine and broke. This state is difficult to detect easily, and even if a fire or the like occurs and the temperature sensor TD detects heat, the control signal will not be reversed and there is a possibility that major damage may occur.

An object of the present invention is to provide a temperature detection device that detects and displays the breakage of the lead wire so that the lead wire can be repaired in advance.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a method for connecting first and second terminals from one terminal of a temperature sensor.
By taking out the third and fourth lead wires from the other terminal and connecting the second and third lead wires through a resistor or constant voltage element, the first to fourth lead wires can be connected. are connected in series, a display is connected in series to this series lead wire group, and the display is configured to be lit by a current flowing through the series lead wire group.

[0008]

[Operation] With the above configuration, when no current flows through the series lead wire group, the indicator goes out and a disconnection is known. Further, due to a change in resistance value between the temperature sensor terminals due to a change in temperature, a change in temperature can be detected by a change in voltage occurring at a resistor in a group of series lead wires or a terminal of a constant voltage element.

[0009]

[Embodiment] (Embodiment 1) Fig. 1 shows a first embodiment of the present invention. 4 is a temperature detection circuit, 1 is a power supply terminal, 2 is a control signal output terminal, IC is a comparator, R1 to R3 are bias resistors of the comparator IC, CN2 is a temperature sensor TD
Connect the two lead wires from both terminals of the temperature detection circuit 4.
The connector D1 connects the first and second lead wires from one terminal of the temperature sensor TD, and the third,
This is a light emitting diode as an indicator that lights up with the current flowing through the series lead wire group formed by pulling out the fourth lead wire.R4 is the current limiting resistor, and R5 is the resistor that forms part of the series lead wire group. , both ends are connected to second and third lead wires, respectively. The first lead wire is connected to the resistor R4, and the fourth lead wire is grounded.

In this case, the relationship of resistance values is R4/R5≫R
2/R3, the terminals of the temperature sensor TD are open and a non-inverted (power supply voltage) is output to the control signal output terminal 2 of the comparator IC, and the terminals of the temperature sensor TD are closed and inverted (grounded). ) is output. Even if the resistance between the terminals of the temperature sensor TD changes from large to small, the output of the comparator IC similarly changes from non-inverted to inverted.

(Embodiment 2) FIG. 2 shows a second embodiment of the present invention. 5 is a temperature detection circuit, TR is a transistor whose base current is the current flowing through the series lead wire group, R6 is its base resistance, and R7 is a resistor forming part of the series lead wire group, with both ends connected to the second and second wires, respectively. Connected to lead wire 3. The first lead wire is connected to the base resistor R6, the fourth
The lead wire is grounded. D2 is a light emitting diode as a display, and R8 is a current limiting resistor thereof, connected in series and inserted between the collector of transistor TR and ground. Other symbols are the same as those used in FIG. However, the resistor R2 is connected to the collector of the transistor TR, so that the base current flows through the transistor TR, and the transistor T
Receives voltage supply only when R is conducting. As in Example 1, by setting the resistance value so that the relationship R6/R7≫R2/R3 holds, the terminals of the temperature sensor TD are open, and the control signal output terminal 2 of the comparator IC has a non-inverted signal. (power supply voltage) is inverted (grounded) when the terminals of the temperature sensor TD are closed.

Even if the resistance between the terminals of the temperature sensor TD changes from large to small, the output of the comparator IC similarly changes from non-inverted to inverted.

In the first embodiment, the temperature sensor T
If any lead wire in the series lead wire group consisting of the four lead wires connected to D and resistor R5 is disconnected,
Current no longer flows through the light emitting diode D1 and the light is turned off, thereby making it possible to notify the disconnection state.

The second embodiment is an improvement on the first embodiment. As in the first embodiment, if any lead wire in the series lead wire group is disconnected, the base current of the transistor TR stops flowing, the transistor TR becomes non-conductive, and the light emitting diode D2 goes out to notify the disconnection state.

Further, the transistor TR becomes non-conductive and the power supply to the resistor R2 is cut off, so that the inverting input terminal of the comparator IC can be grounded.

When the first or second lead wire is disconnected, the non-inverting input terminal of the comparator IC becomes grounded in both the first and second embodiments, and in the first embodiment, the control signal of the comparator IC Whereas an inverted (grounded) signal is output to the output terminal 2, in the second embodiment, the inverted input terminal is also grounded at the same time, and the control signal output terminal 2 of the comparator IC is inverted (grounded). It is possible to display only the disconnection by turning off the light emitting diode D2 without causing any trouble.

[0017]

[Effects of the Invention] As is clear from the above embodiments, the temperature detection device of the present invention displays an indication even if the lead wire connecting the temperature sensor and the temperature detection circuit is broken due to some reason. This is of great industrial value, as it allows users to be informed of the situation, conduct inspections in advance, and prevent damage.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing a first embodiment of the temperature sensing device of the present invention.

[Fig. 2] Electrical circuit diagram showing the second embodiment

[Figure 3] Electrical circuit diagram showing a conventional temperature sensing device

[Explanation of symbols]

1 Power supply terminal 2 Control signal output terminal 4 Temperature detection circuit 5 Temperature detection circuit TD Temperature sensor IC comparator TR transistor CN1, CN2 connector D1, D2 Light emitting diode R1~R8 Resistance

Claims (2)

[Claims] Claim 1: First and second lead wires are taken out from one terminal of a temperature sensor, third and fourth lead wires are taken out from the other terminal, and the second and third lead wires are connected to a conductor. Connect the display and the resistor in series to the power supply, connect the other end to the first lead wire, ground the fourth lead wire, and connect the second and third lead wires to conductivity. Connect one of the connection points of the body to one input terminal of the comparator, and connect a resistor between the other input terminal and the power supply and ground, or use one of the resistors as a constant voltage element to set the reference voltage. The temperature detection device is configured to take out an inverted signal from the output terminal of the comparator when the temperature changes, and to notify the disconnection by turning off the indicator when the lead wire connected to the temperature sensor is disconnected. . [Claim 2] Connecting the emitter of the transistor to a power supply,
The base is connected to the first lead wire of the temperature sensor via a resistor, the fourth lead wire is grounded, and one of the connection points between the second and third lead wires and the conductor is connected to one input terminal of the comparator. Connect a resistor between the other input terminal of the comparator and the collector of the transistor and ground, or use one of the resistors as a constant voltage element to apply a reference voltage, and then adjust the temperature from the output terminal of the comparator. When the temperature sensor changes, an inverted signal is taken out, and an indicator is connected between the collector of the transistor and the ground. When the lead wire connected to the temperature sensor is cut, the transistor becomes non-conductive and the indicator turns off. At this time, the comparator Temperature detection device configured so that the output of the device will not be reversed.